共查询到20条相似文献,搜索用时 406 毫秒
1.
Shi Nian-Qing Prahl Kristine Hendrick Jim Cruz Jose Lu Ping Cho Jae-Yong Jones Sharon Jeffries Thomas 《Applied biochemistry and biotechnology》2000,84(1-9):201-216
Pichia stipitis CBS 6054 will grow on d-xylose, d-arabinose, and l-arabinose. d-Xylose and l-arabinose are abundant in seed hulls of maize, and their utilization is important in processing grain residues. To elucidate
the degradation pathway for l-arabinose, we obtained a mutant, FPL-MY30, that was unable to grow on d-xylose and l-arabinose but that could grow on d-arabinitol. Activity assays of oxidoreductase and pentulokinase enzymes involved in d-xylose, d-arabinose, and l-arabinose pathways indicated that FPL-MY30 is deficient in d-xylitol dehydrogenase (D-XDH), d- and l-arabinitol dehydrogenases, and d-ribitol dehydrogenase. Transforming FPL-MY30 with a gene for xylitol dehydrogenase (PsXYL2), which was cloned from CBS 6054 (Gen Bank AF127801), restored the D-XDH activity and the capacity for FPL-MY30 to grow on
l-arabinose. This suggested that FPL-MY30 is critically deficient in XYL2 and that the d-xylose and l-arabinose metabolic pathways have xylitolas a common intermediate. The capacity for FPL-MY30 to grow on d-arabinitol could proceed through d-ribulose. 相似文献
2.
Arabinose utilization by xylose-fermenting yeasts and fungi 总被引:1,自引:0,他引:1
Various wild-type yeasts and fungi were screened to evaluate their ability to fermentl-arabinose under oxygen-limited conditions when grown in defined minimal media containing mixtures ofl-ara-binose,d-xylose, andd-glucose. Although all of the yeasts and some of the fungi consumed arabinose, arabinose was not fermented to ethanol by any
of the strains tested. Arabitol was the only major product other than cell mass formed froml-arabinose; yeasts converted arabinose to arabitol at high yield. The inability to fermentl-arabinose appears to be a consequence of inefficient or incomplete assimilation pathways for this pentose sugar. 相似文献
3.
Gao Qiang Zhang Min McMillan James D. Kompala Dhinakar S. 《Applied biochemistry and biotechnology》2002,98(1-9):341-355
Zymomonas mobilis has been metabolically engineered to broaden its substrate utilization range to include d-xylose and l-arabinose. Both genomically integrated and plasmid-bearing Z. mobilis strains that are capable of fermenting the pentose d-xylose have been created by incorporating four genes: two genes encoding xylose utilization metabolic enzymes (xylA/xylB) and two genes encoding pentose phosphate pathway enzymes (talB/tktA). We have characterized the activities of the four newly introduced enzymes for xylose metabolism, along with those of three
native glycolytic enzymes, in two different xylose-fermenting Z. mobilis strains. These strains were grown on glucose-xylose mixtures in computer-controlled fermentors. Samples were collected and
analyzed to determine extracellular metabolite concentrations as well as the activities of several intracellular enzymes in
the xylose and glucose uptake and catabolism pathways. These measurements provide new insights on the possible bottlenecks
in the engineered metabolic pathways and suggest methods for further improving the efficiency of xylose fermentation. 相似文献
4.
H. Kindl G. J. Kremlicka O. Hoffmann-Ostenhof 《Monatshefte für Chemie / Chemical Monthly》1966,97(6):1783-1786
Zusammenfassung Die Bildung und das Vorkommen von Cycliten inThuja occidentalis wurden mit Hilfe der Methode der Photoassimilation in einer Atmosphäre von14CO2 untersucht. Nebenmyo-Inosit, Sequoyit,d-chiro-Inosit undd-Pinit wurde auchl-Leucanthemit (l-1,2,4/3-Cyclohexentetrol), ein Cyclit, der bisher nur als Inhaltsstoff mehrerer Angiospermae bekannt ist, nachgewiesen. Das Vorkommen vonl-Leucanthemit konnte auch inPinus austriaca sichergestellt werden. Methoden zur Isolierung vonl-Leucanthemit ausThuja occidentalis wurden ausgearbeitet.
The formation and the occurrence of cyclitols inThuja occidentalis has been studied, using the method of photoassimilation in an atmosphere of14CO2. Besidesmyo-inositol, sequoyitol,d-chiro-inositol, andd-pinitol, alsol-leucanthemitol (l-1,2,4/3-cyclohexentetrol), a cyclitol which so far has only been found in Angiospermae, was identified. The occurrence ofl-leucanthemitol could also be established inPinus austriaca. Methods have been elaborated which permit the isolation ofl-leucanthemitol fromThuja occidentalis.相似文献
5.
N. N. Kabal'nova V. V. Shereshovets Yu. I. Murinov D. V. Kazakov G. R. Abuzarova G. A. Tolstikov 《Russian Chemical Bulletin》1996,45(1):49-51
Rate constants of singlet oxygen quenching by glycyrrhetic acid, glycyrrhizic acid, isoliquiritigenin, licurazide,d-glucose, andl-arabinose were determined. An increase in the quenching rate constants by more than an order of magnitude is observed on going from aglycone to the corresponding glycoside.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 57–59, January, 1996. 相似文献
6.
Eric P. Knoshaug Mary Ann Franden Boris U. Stambuk Min Zhang Arjun Singh 《Cellulose (London, England)》2009,16(4):729-741
l-Arabinose is one of the sugars found in hemicellulose, a major component of plant cell walls. The ability to convert l-arabinose to ethanol would improve the economics of biomass to ethanol fermentations. One of the limitations for l-arabinose fermentation in the current engineered Saccharomyces cerevisiae strains is poor transport of the sugar. To better understand l-arabinose transport and use in yeasts and to identify a source for efficient l-arabinose transporters, 165 non-Saccharomyces yeast strains were studied. These yeast strains were arranged into six groups based on the minimum time required to utilize
20 g/L of l-arabinose. Initial transport rates of l-arabinose were determined for several species and a more comprehensive transport study was done in four selected species.
Detailed transport kinetics in Arxula adeninivorans suggested both low and high affinity components while Debaryomyces hansenii var. fabryii, Kluyveromyces marxianus and Pichia guilliermondii possessed a single component, high affinity active transport systems. 相似文献
7.
Functional expression of a β-d-1,4 glucanase-encoding gene (egl1) from a filamentous fungus was achieved in both Escherichia coli and Saccharomyces cerevisiae using a modified version of pRS413. Optimal activity of the E. coli-expressed enzyme was found at incubation temperatures of 60°C, whereas the enzyme activity was optimal at 40°C when expressed
by S. cerevisiae. Enzyme activity at different pH levels was similar for both bacteria and yeast, being highest at 5.0. Yeast expression resulted
in a highly glycosylated protein of approx 60 kDa, compared to bacterial expression, which resulted in a protein of 30 kDa.
The hyperglycosylated protein had reduced enzyme activity, indicating that E. coli is a preferred vehicle for production scale-up. 相似文献
8.
Nobuhiro Ishida Satoshi Saitoh Toru Ohnishi Kenro Tokuhiro Eiji Nagamori Katsuhiko Kitamoto Haruo Takahashi 《Applied biochemistry and biotechnology》1996,131(1-3):795-807
We developed a metabolically engineered Saccharomyces cerevisiae, which produces optically pure l-lactic acid efficiently using cane juice-based medium. In this recombinant, the coding region of pyruvate decarboxylase (PDC)1 was completely deleted, and six copies of the bovine l-lactate dehydrogenase (l-LDH) genes were introduced on the genome under the control of the PDC1 promoter. To confirm optically pure lactate production in lowcost medium, cane juice-based medium was used in fermentation
with neutralizing conditions. l-lactate production reached 122 g/L, with 61% of sugar being transformed into l-lactate finally. The optical purity of this l-lactate, that affects the physical characteristics of poly-l-lactic acid, was extremely high, 99.9% or over.
These two authors contributed equally to this work. 相似文献
9.
This work represents a continuation of our investigation into environmental conditions that promote lactic acid synthesis
by Zymomonas mobilis. The characteristic near theoretical yield of ethanol from glucose by Z. mobilis can be compromised by the synthesis of d- and l-lactic acid. The production of lactic acid is exacerbated by the following conditions: pH 6.0, yeast extract, and reduced
growth rate. At a specific growth rate of 0.048/h, the average yield of dl-lactate from glucose in a yeast extract-based medium at pH 6.0 was 0.15 g/g. This represents a reduction in ethanol yield
of about 10% relative to the yield at a growth rate of 0.15/h. Very little lactic acid was produced at pH 5.0 or using a defined
salts medium (without yeast extract) Under permissive and comparable culture conditions, a tetracycline-resistant, d-ldh negative mutant produced about 50% less lactic acid than its parent strain Zm ATCC 39676. d-lactic acid was detected in the cell-free spent fermentation medium of the mutant, but this could be owing to the presence
of a racemase enzyme. Under the steady-state growth conditions provided by the chemostat, the specific rate of glucose consumption
was altered at a constant growth rate of 0.075/h. Shifting from glucose-limited to nitrogen-limited growth, or increasing
the temperature, caused an increase in the specific rate of glucose catabolism. There was good correlation between an increase
in glycolytic flux and a decrease in lactic acid yield from glucose. This study points to a mechanistic link between the glycolytic
flux and the control of end-product glucose metabolism. Implications of reduced glycolytic flux in pentose-fermenting recombinant
Z. mobilis strains, relative to increased byproduct synthesis, is discussed. 相似文献
10.
Jie Lü Xiang Jin Pei-Hong Mao Xiang-Dong Ma Hai-Qiu Ling Yong-Hong Fan Long Yu Bao-Shan Wu Ping-Kai Ouyang 《Applied biochemistry and biotechnology》2009,158(3):571-581
The genomic DNA from Ephedra glauca was randomly transferred to Saccharomyces cerevisiae and Hansenula anomala by argon and nitrogen ion implantation. Through repeated subculturing and using reversed phase high-performance liquid chromatography
analysis to quantify the concentrations of the secondary metabolites, l-ephedrine and d-pseudoephedrine, 12 recombinant strains of genetically stable yeast were obtained, each using glucose as a carbon source,
NaNO3 as a nitrogen source and producing l-ephedrine and/or d-pseudoephedrine. After culturing in liquid medium for 72 h, extracellular l-ephedrine and d-pseudoephedrine concentrations of 18.85 and 4.11 mg/L, respectively, were detected. Using l-ephedrine and d-pseudoephedrine as the target products, the transformation efficiencies of the genomic DNA from E. glauca transferred to S. cerevisiae and H. anomala were 1.15% (1/87) and 2.13% (8/376), respectively. The addition of the amino acid, L-Phe, to culture media substantially
changed the amount of l-ephedrine and/or d-pseudoephedrine produced by the recombined yeasts. However, the change in metabolite production was not consistent among
strains, rising in some, while dropping to nondetectable levels in others. After random amplification of polymorphic DNA (RAPD)
analysis, four RAPD primers were obtained from the initial 100 RAPD primers, each amplifying different fragments with the
recombined yeast Ar_Han0458 genome. Using one primer as polymerase chain reaction primer, the result showed that the recombined
yeast Ar_Han0458 genome matched E. glauca genomic DNA at 150 bp, indicating a successful transfer of genetic information, facilitated by ion implantation. 相似文献
11.
Monoalkylation of amino acids of different structural types withN-chloroacetyl-glycosylamines was shown to be applicable for the preparation of glycoconjugates containing β-d-galactose,N-acetyl-β-d-glucosamine, β-d-mannose, and lactose residues. The glycoconjugates were synthesized from amino acids with secondary (sarcosine,l-proline) or primary (l-2- and 4-aminobutyric acids,l-tryptophan) amino groups as well as from various amino dicarboxylic acids (N-methyl-dl-aspartic,dl-aspartic,l-glutamic, anddl-2-aminoadipic acids). The derivatives obtained may be of interest for glycotargeting of physiologically active compounds
of this series.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1377–1380, July, 1999. 相似文献
12.
We changed the fluxes of xylose metabolites in recombinant Saccharomyces cerevisiae by manipulating expression of Pichia stipitis genes (XYL1 and XYL2) coding for xylose reductase (XR) and xylitol dehydrogenase (XDH), respectively. XYL1 copy number was kept constant by integrating it into the chromosome. Copy numbers of XYL2 were varied either by integrating XYL2 into the chromosome or by transforming cells with XYL2 in a multicopy vector. Genes in all three constructs were under control of the strong constitutive glyceraldehyde-3-phosphate
dehydrogenase promoter. Enzymatic activity of XR and XDH in the recombinant strains increased with the copy number of XYL1 and XYL2. XR activity was not detected in the parent but was present at a nearly constant level in all of the transformants. XDH activity
increased 12-fold when XYL2 was on a multicopy vector compared with when it was present in an integrated single copy. Product formation during xylose
fermentation was affected by XDH activity and by aeration in recombinant S. cerevisiae. Higher XDH activity and more aeration resulted in less xylitol and more xylulose accumulation during xylose fermentation.
Secretion of xylulose by strains with multicopy XYL2 and elevated XDH supports the hypothesis that d-xylulokinase limits metabolic flux in recombinant S. cerevisiae. 相似文献
13.
Egressy-Molnár O Vass A Németh A García-Reyes JF Dernovics M 《Analytical and bioanalytical chemistry》2011,401(1):373-380
Effects of the two most widespread sample preparation techniques on the d,l-enantiomer ratio of extracted selenomethionine were monitored through the analysis of the certified reference material selenium-enriched
yeast and the isolated protein fraction of high selenium monkeypot nut. The extracted selenomethionine (SeMet) fractions were
orthogonally cleaned up with anion exchange chromatography before carrying out the enantiomer-specific detection to increase
the robustness and the efficiency of the subsequent o-phthal-aldehyde and n-isobutyril-cysteine-based derivatisation process and reversed phase-high-performance liquid chromatography-inductively coupled
plasma mass spectroscopy (ICP-MS) detection. The two techniques, namely methanesulphonic acid (MSA) based digestion and proteolytic
digestion with protease XIV, resulted in significantly different ratio of d,l-selenomethionine with the final results of 2.2–2.7% and 0.5–0.6% of d-SeMet, respectively. The study revealed significant differences in the ICP-MS-related sensitivity of the derivatised selenomethionine
enantiomers, which calls attention to the quantification of this selenoamino acid after MSA hydrolysis. 相似文献
14.
Zusammenfassung Das Vorkommen von Cycliten inChlorella fusca wurde mit Hilfe der Methode der Photoassimilation in einer Atmosphäre von14CO2 untersucht. Außer dem bereits als Bestandteil dieser Algenart bekanntenmyo-Inosit konnten auch andere Cyclite, nämlichd-chiro-Inosit, Mytilit, Laminit undl-Leucanthemit nachgewiesen werden. Einbauversuche mit markierten Vorstufen ergaben, daßmyo-Inosit höchstwahrscheinlich auf dem schon in vielen Organismen nachgewiesenen Weg ausd-Glucose entsteht undd-chiro-Inosit das Produkt einer direkten Epimerisierung vonmyo-Inosit ist. Hingegen besteht keine biogenetische Beziehung zwischenmyo-Inosit und den beiden C-Methylinositen Mytilit und Laminit; die Methylgruppe vonl-Methionin wird nicht in diese beiden Verbindungen eingebaut.
21. Mitt.:E. Molinari undO. Hoffmann-Ostenhof,Z. physiol. Chem.349, 1797 (1968). 相似文献
Studies on the biosynthesis of the cyclitols, XXII: Cyclites in chlorella fusca
The occurrence of cyclitols inChlorella fusca has been studied, using the method of photoassimilation in an atmosphere of14CO2. Besidesmyo-inositol which is known to be a constituent of this algal species, other cyclitols were detected, namelyd-chiro-inositol, mytilitol, laminitol, andl-leucanthemitol. Incorporation experiments with labelled precursors make it most probable thatmyo-inositol is formed fromd-glucose through a pathway already established in many organisms, whereasd-chiro-inositol is the product of a direct epimerization ofmyo-inositol. No biogenetic relation exists betweenmyo-inositol and the two C-methylinositols; the methyl group ofl-methionine is not incorporated into these compounds.
21. Mitt.:E. Molinari undO. Hoffmann-Ostenhof,Z. physiol. Chem.349, 1797 (1968). 相似文献
15.
Drying dissipative structures of aqueous solutions of poly-d-lysine hydrobromide, poly-l-lysine hydrobromide, and their low-molecular-weight analogs were studied on a cover glass, a watch glass, and a Petri glass
dish. Size of the broad rings, one of the typical macroscopic patterns, decreased as the solute concentration decreased. Microscopic
drying crystal patterns of polylysine hydrobromides and their low-molecular-weight analogs, i.e., d-, l-, and dl-lysine hydrochloride changed as a function of the distance from the film center, which is one of the typical features of
dissipative crystallization. Macroscopic and microscopic drying patterns were quite similar to each other irrespective of their stereospecificity. The
crystal patterns of the mixtures of poly-d-lysine hydrobromide and poly-l-lysine hydrobromide were also similar to those of the corresponding single-component polymers. The stereospecific effects
were not observed in this work. 相似文献
16.
Zusammenfassung Injiziert man Ratten i. p. 1,1-Diäthoxy-4-hydroxy-2-penten, so wird die Verbindung rasch resorbiert und metabolisiert. Im Harn können 6 Metaboliten nachgewiesen werden. Zwei davon wurden als diastereomere Mercaptursäuren identifiziert, nämlich als die N-Acetyl-S-(d-bzw.l-1-diäthoxymethyl-3-oxobutyl)-l-cysteine. Der Bildungsweg dieser Verbindungen wird besprochem.
Mit 1 Abbildung
Herrn Prof. Dr. Dr. h. c.Otto Kratky mit den besten Wünschen zum 70. Geburtstag gewidmet. 相似文献
Mercapturic acid formation during detoxication of 1,1-diethoxy-4-hydroxy-2-pentene
Following intraperitoneal administration to rats 1.1-diethoxy-4-hydroxy-2-pentene is rapidly resorbed and metabolized. Among six metabolites excreted in rat urine two have been identified as the diastereomeric mercapturic acids, N-acetyl-S-(d-1-diethoxymethyl-3-oxo-butyl)-l-cysteine and N-acetyl-S-(l-1-diethoxymethyl-3-oxobutyl)-l-cysteine. The metabolic formation of these compounds is discussed.
Mit 1 Abbildung
Herrn Prof. Dr. Dr. h. c.Otto Kratky mit den besten Wünschen zum 70. Geburtstag gewidmet. 相似文献
17.
Extracellular Production and Characterization of <Emphasis Type="BoldItalic">Streptomyces</Emphasis> X-prolyl Dipeptidyl Aminopeptidase 总被引:1,自引:0,他引:1
Hatanaka T Yamasato A Arima J Usuki H Yamamoto Y Kumagai Y 《Applied biochemistry and biotechnology》2011,164(4):475-486
X-prolyl dipeptidyl aminopeptidases (X-PDAPs) are useful in various food industries. In this study, we performed sequence-based
screening to obtain a stable X-PDAP enzyme from thermophilic Streptomyces strains. We found three genes that encoded X-PDAP from Streptomyces thermoluteus subsp. fuscus NBRC 14270 (14270 X-PDAP), Streptomyces thermocyaneoviolaceus NBRC 14271 (14271 X-PDAP), and Streptomyces thermocoerulescens NBRC 14273, which were subsequently cloned and sequenced. The deduced amino acid sequences of these genes showed high similarity,
with ~80% identity with each other. The isolated X-PDAPs and an X-PDAP from Streptomyces coelicolor were expressed in Streptomyces lividans using a hyperexpression vector: pTONA5a. Among these genes, only 14270 and 14271 X-PDAPs caused overexpression and extracellular production without artificial signal
peptides. We also characterized the biochemical properties of purified 14271 X-PDAP. In addition, we found that, in peptide
synthesis via an aminolysis reaction, this enzyme recognized d-amino acid derivatives as acyl acceptors, similar to l-amino acid derivatives. 相似文献
18.
d-Xylose is a major constituent of hemicellulose, which makes up 20–30% of renewable biomass in nature.d-Xylose can be fermented by most yeasts, includingSaccharomyces cerevisiae, by a two-stage process. In this process, xylose is first converted to xylulose in vitro by the enzyme xylose (glucose) isomerase,
and the latter sugar is then fermented by yeast to ethanol. With the availability of an inexpensive source of xylose isomerase
produced by recombinantE. coli, this process of fermenting xylose to ethanol can become quite effective. In this paper, we report that yeast xylose and
xylulose fermentation can be further improved by cloning and overexpression of the xylulokinase gene. For instance, the level
of xylulokinase activity in S.cerevisiae can be increased 230fold by cloning its xylulokinase gene on a high copy-number plasmid, coupled with fusion of the gene
with an effective promoter. The resulting genetically-engineered yeasts can ferment xylose and xylulose more than twice as
fast as the parent yeast. 相似文献
19.
Four chiral derivatizing reagents (CDR 1–4), namely, FDNP-l-Ala, FDNP-l-Val, FDNP-l-Phe, and FDNP-l-Leu, were synthesized using microwave (MW) irradiation by substituting one of the fluorine atoms in difluoro dinitro benzene
(DFDNB) with l-Ala, l-Val, l-Phe, and l-Leu (CDR 1–4). The other set of CDRs, namely, FDNP-l-Phe-NH2, FDNP-l-Val-NH2, and FDNP-l-Leu-NH2, was also prepared. These reagents were used for synthesis of diastereomers of 18 proteinogenic and 08 non-proteinogenic
amino acids, which were resolved by reversed-phase high-performance liquid chromatography using C18 column and gradient eluting
mixture of aq.TFA and acetonitrile with UV detection at 340 nm. The reagents were used for resolution of a complex mixture
of 18 racemic proteinogenic amino acids in a single chromatographic run of 65 min and to determine concentration of the d-amino acid in a solution of dl-amino acid. The resolution (R
S) and selectivity (α) obtained for the two sets of diastereomers were compared among themselves and among the two groups. The method was validated
for accuracy, precision, limit of detection (LOD), and limit of quantification. LOD is 0.001% impurity of d-enantiomer. 相似文献
20.
de Almeida MN Guimarães VM Bischoff KM Falkoski DL Pereira OL Gonçalves DS de Rezende ST 《Applied biochemistry and biotechnology》2011,165(2):594-610
The aim of this work was to have cellulase activity and hemicellulase activity screenings of endophyte Acremonium species (Acremonium zeae EA0802 and Acremonium sp. EA0810). Both fungi were cultivated in submerged culture (SC) containing l-arabinose, d-xylose, oat spelt xylan, sugarcane bagasse, or corn straw as carbon source. In solid-state fermentation, it was tested as
carbon source sugarcane bagasse or corn straw. The highest FPase, endoglucanase, and xylanase activities were produced by
Acremonium sp. EA0810 cultivated in SC containing sugarcane bagasse as a carbon source. The highest β-glucosidase activity was produced
by Acremonium sp. EA0810 cultivated in SC using d-xylose as carbon source. A. zeae EA0802 has highest α-arabinofuranosidase and α-galactosidase activities in SC using xylan as a carbon source. FPase, endoglucanase,
β-glucosidase, and xylanase from Acremonium sp. EA0810 has optimum pH and temperatures of 6.0, 55 °C; 5.0, 70 °C; 4.5, 60 °C; and 6.5, 50 °C, respectively. α-Arabinofuranosidase
and α-galactosidase from A. zeae EA0802 has optimum pH and temperatures of 5.0, 60 °C and 4.5, 45 °C, respectively. It was analyzed the application of Acremonium sp. EA0810 to hydrolyze sugarcane bagasse, and it was achieved 63% of conversion into reducing sugar and 42% of conversion
into glucose. 相似文献